1. Field of the Invention
The present invention relates generally to the movement of electrodes used in the processing of materials. This invention finds particular application in conjunction with the transportation of carbon based electrodes used to transmit energy used to process metal in metallurgical vessels, including electric arc furnace systems. More particularly, but without limitation, this invention relates to the manual assembly and disassembly of the apparatus with respect to a graphite electrode to facilitate transportation and holding of the graphite electrode used in a metal processing procedure.
2. Discussion of the Art
It will be appreciated by those skilled in the art that metallurgical vessels are used in the processing of molten materials to house the molten material during the heating step of the processing. These metallurgical vessels can process such molten materials as steel and slag. Carbon based electrodes are used to transmit the energy to the materials housed within the metallurgical vessels. These conventional metallurgical vessels include cooling systems used to regulate the temperature of the metallurgical vessels. For example, furnace systems of the types disclosed in U.S. Pat. Nos. 4,715,042, 4,813,055, 4,815,096 and 4,849,987 are types of these conventional metallurgical vessels.
Graphites electrodes are one type of carbon based material used to comprise the energy transferring electrodes used in metallurgical vessels. Graphite electrodes are used in the steel industry to melt the metals and other ingredients used to form steel in electrothermal furnaces. The heat needed to melt metals is generated by passing current through one or a plurality of electrodes, usually three, and forming an arc between the electrodes and the metal. Electrical currents in excess of 100,000 amperes are often used. The resulting high temperature melts the metals and other ingredients. Generally, the electrodes used in steel furnaces each consist of electrode columns, that is, a series of individual electrodes joined to form a single column. In this way, as electrodes are depleted during the thermal process, replacement electrodes can be joined to the column to maintain the length of the column extending into the furnace.
Conventionally, electrodes are joined into columns via a pin (sometimes referred to as a nipple) that functions to join the ends of adjoining electrodes. Typically, the pin takes the form of opposed male threaded sections or tangs, with at least one end of the electrodes comprising female threaded sections capable of mating with the male threaded section of the pin. Thus, when each of the opposing male threaded sections of a pin are threaded into female threaded sections in the ends of two electrodes, those electrodes become joined into an electrode column. Commonly, the joined ends of the adjoining electrodes, and the pin therebetween, are referred to in the art as a joint.
Alternatively, the electrodes are formed with a male threaded protrusion or tang machined into one end and a female threaded socket machined into the other end, such that the electrodes can be joined by threading the male tang of one electrode into the female socket of a second electrode, and thus form an electrode column. The joined ends of two adjoining electrodes in such an embodiment is referred to in the art as a male-female joint.
Given the extreme thermal stress that the electrode and the joint (and indeed the electrode column as a whole) undergoes, mechanical/thermal factors such as strength, thermal expansion, and crack resistance must be carefully balanced to avoid damage or destruction of the electrode column or individual electrodes. For instance, longitudinal (i.e., along the length of the electrode/electrode column) thermal expansion of the electrodes, especially at a rate different than that of the pin, can force the joint apart, reducing effectiveness of the electrode column in conducting the electrical current. A certain amount of transverse (i.e., across the diameter of the electrode/electrode column) thermal expansion of the pin in excess of that of the electrode may be desirable to form a firm connection between pin and electrode; however, if the transverse thermal expansion of the pin greatly exceeds that of the electrode, damage to the electrode or separation of the joint may result. Again, this can result in reduced effectiveness of the electrode column, or even destruction of the column if the damage is so severe that the electrode column fails at the joint section. Thus, control of the thermal expansion of an electrode, in both the longitudinal and transverse directions, is of paramount importance.
Correspondingly, the transfer and positioning of these graphite electrodes during the metallurgical processes is also important. This is because any damage experienced by the electrodes in their handling, movement, and positioning before, during, and after a given metallurgical process can also result in reduced effectiveness, and/or destruction, of an electrode column.
Conventionally, the electric arc furnace industry uses what is known in the art as a “Threaded Stem Lift Plug” to transport the electrodes. The Threaded Stem Lift Plug is inserted into the female end of the electrode, and normally threaded into position. This threaded stem lift plug cannot attach to the threaded male end of an electrode.
What is needed, then, is a transport apparatus and method for transporting carbon based electrodes used to transmit energy in the processing of metal in metallurgical vessels. This needed transport apparatus and method for transporting can preferably include a shaped aperture positioned to removably engage the electrodes and transport the electrodes for processing. This needed transport apparatus and method for transporting can preferably be shaped to and comprised of materials that allow manual assembly and disassembly of the apparatus with respect to the electrode. This transport apparatus and method for transporting is currently lacking in the art.